Cancers are a leading cause of death in animals and humans. The exact cause of cancer is not known, but links between certain activities such as smoking or exposure to carcinogens and the incidence of certain types of cancers and tumors has been shown by a number of researchers.
Many types of chemotherapeutic agents have been shown to be effective against cancers and tumor cells, but not all types of cancers and tumors respond to these agents. Unfortunately, many of these agents also destroy normal cells. The exact mechanism for the action of these chemotherapeutic agents are not always known.
Despite advances in the field of cancer treatment the leading therapies to date are surgery, radiation and chemotherapy. Chemotherapeutic approaches are said to fight cancers that are metastasized or ones that are particularly aggressive. Such cytocidal or cytostatic agents work best on cancers with large growth factors, i.e., ones whose cells are rapidly dividing. To date, hormones, in particular estrogen, progesterone and testosterone, and some antibiotics produced by a variety of microbes, alkylating agents, and anti-metabolites form the bulk of therapies available to oncologists. Ideally cytotoxic agents that have specificity for cancer and tumor cells while not affecting normal cells would be extremely desirable. Unfortunately, none have been found and instead agents that target especially rapidly dividing cells (both tumor and normal) have been used.
Clearly, the development of materials that would target cancer cells due to some unique specificity for them would be a breakthrough. Alternatively, materials that were cytotoxic to cancer cells while exerting mild effects on normal cells would be desirable.
Human Immunodeficiency Virus (HIV), the etiological agent for AIDS (acquired immune deficiency syndrome), is a member of the lentiviruses, a subfamily of retroviruses. HIV integrates its genetic information into the genome of the host. Most importantly, HIV infects and invades cells of the immune system; it breaks down the body's immune system and renders the patient susceptible to opportunistic infections and neoplasms. HIV-1 is cytopathic for T4 lymphocytes, cells of the immune system that express the cell surface differentiation antigen CD4. In addition to CD4+ T cells, the host range of HIV includes cells of the mononuclear phagocytic lineage, including blood monocytes, tissue macrophages, Langerhans cells of the skin and dendritic reticulum cells within lymph nodes.
Precursor cells in the bone marrow are released into the blood in an immature circulating form known as monocytes. Monocytes use the blood strictly as a transport medium. Once they arrive where they're going to be used, they leave the blood and complete differentiation into macrophages. Cells of the monocyte/macrophage lineage are a major target population for infection with HIV in the body and are thought to provide reservoirs of virus for disseminating infection throughout the body. HIV is also neurotropic, capable of infecting monocytes and macrophages in the central nervous system causing severe neurologic damage. They can interact and fuse with CD4-bearing T cells, causing T cell depletion and thus contributing to the pathogenesis of AIDS.
Progression from HIV infection to AIDS is primarily determined by the effects of HIV on the cells that it infects, including CD4+ T lymphocytes and macrophages. In turn, cell activation, differentiation and proliferation regulate HIV infection and replication in those cells. HIV and other lentiviruses can proliferate in nonproliferating, terminally differentiated macrophages and growth-arrested T lymphocytes. This ability of lentiviruses, including HIV, to replicate in nonproliferating cells, particularly in macrophages, is believed to be unique among retroviruses.
Due to the above-mentioned problems in the art, the present inventors have sought improvements and provide such improvements herein.
Carbendazim, or 2-methoxycarbonylaminobenzimidazole, has been studied as a cancer treatment. See U.S. Pat. No. 5,767,138 issued Jun. 16, 1998 to J. B. Camden. Carbendazim metabolizes in the body through the hydroxylation of the benzene ring, primarily in the 5-position. The metabolite is not as active in the treatment of cancer as the 2-methoxycarbonylaminobenzimidazole. Moreover, this compound is not very soluble. A derivative that maintains the activity of the benzimidazole but is more soluble is highly preferred. It has been found that substituted benzimidazole carbamates, and in particular, those claimed herein are more soluble, yet maintain cytotoxic behavior.